ON THE EFFECTS OF 2ND-PHASE DISTRIBUTION ON THE FRACTURE-BEHAVIOR OF 2 SUPERPLASTIC ALUMINUM-ALLOYS

The significant scatter observed in the elongation to fracture of spec imens taken from a single, industrially processed sheet for two Al all oys has been traced to changes in the value of the strain rate sensiti vity index (m) and also to the specimen to specimen variation in the c oncentration and distribution of second phase particles/inclusions. It is shown that these three variables of m, second phase particle conte nt and distribution affect the width of tear ridges, the size of clust ers of grains that pull out as a whole during fracture, their connecti vity and the extent to which cavitation can be suffered before final f racture. The consequences of these effects for specimen ductility are discussed.